Agency Publishes Final Toxicological Profiles for Lead and Glyphosate
Final toxicological profiles for lead and glyphosate are now available from the Agency for Toxic Substances and Disease Registry. ATSDR’s “Tox Profiles” characterize the toxicological and adverse health effects information for hazardous substances. According to ATSDR, the general population is primarily exposed to lead via the oral route, with some contribution from the inhalation route. The agency notes that inhalation exposures can be more important in occupational settings, depending on the particle size. Occupational exposure to organic lead compounds may also involve dermal absorption as an exposure route. ATSDR’s profile for lead does not attempt to separate health effects by exposure route because “the primary systemic toxic effects of [lead] are the same regardless of the route of entry into the body.” The U.S. National Toxicology Program, which prepares the Report on Carcinogens, has determined that lead and lead compounds are reasonably anticipated to be human carcinogens (PDF). EPA classifies lead as a probable human carcinogen. And in a monograph published in 2006 (PDF), the International Agency for Research on Cancer states that inorganic lead compounds are probably carcinogenic to humans and that there is “inadequate evidence” to determine whether organic lead compounds will cause cancer in humans. ATSDR’s profile for glyphosate explains that human exposures to the chemical are to herbicides that contain glyphosate and other ingredients, and that human studies have reported possible associations between glyphosate herbicide use and various health outcomes. However, glyphosate formulations vary in specific components and their relative proportions, which ATSDR says precludes “meaningful comparisons of toxic effect levels.” Despite its herbicidal applications, glyphosate is unlikely to accumulate in the environment, because it is easily either degraded by microbes or inactivated by absorption into the soil. Glyphosate is the active ingredient in a variety of broad-spectrum herbicidal products for residential, commercial, and agricultural uses. According to ATSDR, it is typically manufactured for commercial use as a salt available in soluble liquid and granule formulations. “The highest potential for dermal, inhalation, and ocular exposure is expected for pesticide applicators, farm workers, and home gardeners who use herbicides containing glyphosate,” the toxicological profile explains. Earlier this year, EPA announced its conclusion that glyphosate is not a carcinogen and poses no risks to public health when used in accordance with its label. There is no OSHA permissible exposure limit for glyphosate. In 2015, IARC classified glyphosate as “probably carcinogenic to humans.” A working group convened by IARC found “limited evidence” in humans for the carcinogenicity of glyphosate but cited a positive association for non-Hodgkin lymphoma. According to the monograph, there is “sufficient evidence” that glyphosate causes cancer in experimental animals. More information on ATSDR’s toxicological profiles is available on the agency's website.